Skin cancers from exposure to sunlight and ultraviolet radiation are the most common form of cancer, with more than 400,000 new cases per year, and with incidence rates rising rapidly for all types of skin cancer. Yet the behavioral sciences have been slow to recognize the existence and extent of the problem. What few studies there are have been designed primarily to assess knowledge about skin cancer, sun exposure, and sunscreen use and to assess the behavioral correlates of sun exposure and sunscreen use. None of these studies has adopted a well-articulated model of behavior change to guide either the collection of data or the design of interventions. The objective of this project is to develop and test an integrated series of theory-based self-report measures designed to assess behaviors and intentions towards reducing sun and ultraviolet light exposure. The theoretical basis for these measures will be the Transtheoretical Model, a stage and process model of problem behavior change. To date, this model has been successfully applied to several cancer risk factors and health behavior problems, including smoking, alcohol abuse, weight control, exercise, safer sex practices, and psychological distress. This project represents the first step in the adaptation of the Transtheoretical Model to the problem of sun exposure. Specific measures to be developed include questionnaires to assess: stages of change, processes of change, decisional balance, and self-efficacy. Measurement development will follow standard psychometric procedures. An initial sample of 300 college students will be used for preliminary test development, refinement of the item pool and exploratory dimensional analyses. Revised questionnaires will then be administered to a new sample of 300 subjects recruited from area beaches. These data will be used to confirm the expected structure of the measures through the use of structural equation modeling. The results of these exploratory and confirmatory analyses will be the development of short, reliable, and valid measures of sun exposure behaviors and intentions. Ultimately, the construction of such a set of measurement instruments will be necessary for the development of phase II and III prospective and intervention studies of sun exposure.